Perovskite type oxide, ferroelectric film, process for producing same, ferroelectric device, and liquid discharge apparatus

Abstract

A perovskite type oxide that is represented by Formula (P) shown below is provided: (Pb 1−x+δ M x ) (Zr y Ti 1−y )O z   (P) wherein M represents at least one kind of element selected from the group consisting of Bi and lanthanide elements, x represents a number satisfying the condition of 0.05≦x≦0.4, and y represents a number satisfying the condition of 0<y≦0.7, the standard composition being such that δ=0, and z=3, with the proviso that the value of δ and the value of z may deviate from the standard values of 0 and 3, respectively, within a range such that the perovskite structure is capable of being attained.

1 . A perovskite type oxide that is represented by Formula (P) shown below:
   (Pb 1−x+δ M x) (Zr   y Ti 1−y )O z    (P)   
     wherein M represents at least one kind of element selected from the group consisting of Bi and lanthanide elements,
 x represents a number satisfying the condition of 0.05≦x≦0.4, and 
 y represents a number satisfying the condition of 0<y≦0.7, 
 the standard composition being such that δ=0, and z−3, with the proviso that the value of δ and the value of z may deviate from the standard values of 0 and 3, respectively, within a range such that the perovskite structure is capable of being attained. 
 
   
   
       2 . A perovskite type oxide as defined in  claim 1  wherein M represents Bi. 
   
   
       3 . A perovskite type oxide as defined in  claim 1  wherein x represents a number satisfying the condition of 0.05≦x≦0.25. 
   
   
       4 . A perovskite type oxide as defined in  claim 1  wherein δ represents a number satisfying the condition of 0<δ≦0.2. 
   
   
       5 . A perovskite type oxide as defined in  claim 1  wherein the perovskite type oxide is substantially free from Si, Ge, and V. 
   
   
       6 . A ferroelectric film, containing a perovskite type oxide as defined in  claim 1 . 
   
   
       7 . A ferroelectric film as defined in  claim 6  wherein the ferroelectric film has characteristics such that a value of (Ec 1 +Ec 2 )/(Ec 1 −Ec 2 )×100 (%) is equal to at most 25%, wherein Ec 1  represents the coercive field on the positive electric field side in a bipolar polarization-electric field curve, and Ec 2  represents the coercive field on the negative electric field side in the bipolar polarization-electric field curve. 
   
   
       8 . A ferroelectric film as defined in  claim 6  wherein the ferroelectric film has a film structure containing a plurality of pillar-shaped crystals. 
   
   
       9 . A ferroelectric film as defined in  claim 6  wherein the ferroelectric film has a film thickness of at least 3.0 μm. 
   
   
       10 . A ferroelectric film as defined in  claim 6  wherein the ferroelectric film has been formed by non-thermal-equilibrium processing. 
   
   
       11 . A ferroelectric film as defined in  claim 10  wherein the ferroelectric film has been formed by a sputtering technique. 
   
   
       12 . A ferroelectric film as defined in  claim 11  wherein the ferroelectric film has been formed under film formation conditions satisfying Formulas (1) and (2) shown below:
     Ts (° C.)≧400   (1)     −0.2 Ts+ 100< Vs−Vf ( V )<−0.2 Ts+ 130   (2),   
     wherein Ts (° C.) represents the film formation temperature, and Vs−Vf (V) represents the difference between the plasma potential Vs (V) in the plasma at the time of the film formation and the floating potential Vf (V). 
   
   
       13 . A ferroelectric film as defined in  claim 11  wherein the ferroelectric film has been formed under film formation conditions satisfying Formulas (1), (2), and (3) shown below:
     Ts (° C.)≧400   (1)     −0.2 Ts+ 100< Vs−Vf ( V )<−0.2 Ts+ 130   (2)     10≦ Vs−Vf ( V )≦35   (3),   
     wherein Ts (° C.) represents the film formation temperature, and Vs−Vf (V) represents the difference between the plasma potential Vs (V) in the plasma at the time of the film formation and the floating potential Vf (V). 
   
   
       14 . A process for producing a ferroelectric film as defined in  claim 6 ,
 wherein the ferroelectric film is formed by non-thermal-equilibrium processing.   
   
   
       15 . A process for producing a ferroelectric film as defined in  claim 14  wherein the ferroelectric film is formed by a sputtering technique. 
   
   
       16 . A process for producing a ferroelectric film as defined in  claim 15  wherein the ferroelectric film is formed under film formation conditions satisfying Formulas (1) and (2) shown below:
     Ts (° C.)≧400   (1)     −0.2 Ts+ 100< Vs−Vf ( V )<−0.2 Ts+ 130   (2),   
     wherein Ts (° C.) represents the film formation temperature, and Vs−Vf (V) represents the difference between the plasma potential Vs (V) in the plasma at the time of the film formation and the floating potential Vf (V). 
   
   
       17 . A process for producing a ferroelectric film as defined in  claim 15  wherein the ferroelectric film is formed under film formation conditions satisfying Formulas (1), (2), and (3) shown below:
     Ts (° C.)≧400   (1)     −0.2 Ts+ 100< Vs−Vf ( V )<−0.2 Ts+ 130   (2)     10≦ Vs−Vf ( V )≦35   (3),   
     wherein Ts (° C.) represents the film formation temperature, and Vs−Vf (V) represents the difference between the plasma potential Vs (V) in the plasma at the time of the film formation and the floating potential Vf (V). 
   
   
       18 . A ferroelectric device, comprising:
 i) a ferroelectric film as defined in  claim 6 , and   ii) electrodes for applying an electric field across the ferroelectric film.   
   
   
       19 . A liquid discharge apparatus, comprising:
 i) a piezoelectric device, which is constituted of a ferroelectric device as defined in  claim 18 , and   ii) a liquid storing and discharging member provided with:
 a) a liquid storing chamber, in which a liquid is to be stored, and 
 b) a liquid discharge opening, through which the liquid is to be discharged from the liquid storing chamber to the exterior of the liquid storing chamber.